Inundative Biological Control ofHelicoverpa zea(Lepidoptera: Noctuidae) with the Entomopathogenic NematodeSteinernema riobravis(Rhabditida: Steinernematidae)

The entomopathogenic nematodeSteinernema riobravisCabanillas, Poinar and Raulston (Rhabditida: Steinernematidae) was evaluated for inundative biological control ofHelicoverpa zea(Boddie) (Lepidoptera: Noctuidae) in Arkansas corn fields. Infection ofH. zeawas highly significant in nematode-treated plots of field corn and sweet corn in Little River and Washington Counties, respectively. Mean mortalities fromS. riobravisinfections were 79.2 and 91.3% at treatment levels of 3.7 × 106and 1.2 × 107nematodes/m2of soil, respectively, in Little River County and 78.5 and 94.8% at treatment levels of 5.2 × 105and 5.3 × 106nematodes/m2of soil, respectively, in Washington County. Comparison of irrigated and nonirrigated plots in both counties resulted in no significant differences inS. riobravisinfectingH. zea. S. riobravismay have promise as an inundative biological control agent againstH. zeain Arkansas soils.